A variety of applications require cooling of devices that have very high heat fluxes, such as in the range of 50-1000 W/cm2. These devices include integrated electronic circuits in microprocessors, laser diodes, and power semiconductor devices for control electronics.
In conventional electronic systems, such as computers, heat generated by one or more of these heat-generating devices is transferred to its surroundings through the use of a heat sink and one or more fans. Conventional heat sinks are passive except for the use of the fans, which can be controlled based on a signal from a temperature sensor within the computer or on the heat-generating device. The fans draw cool air into the heat sink and push warm air out. There may also be fans mounted directly on the heat sink. In some circumstances, the fan speed is controlled such that it increases when the device gets warmer and decreases when the device gets cooler. The goals of the heat sink and fan assembly are generally to keep the device below an acceptable maximum temperature.
What is needed is an improved cooling system that regulates both pump and fan speed in a concerted manner to maintain a heat-generating device within its allowed temperature range while conserving power and reducing system noise and transients thereof.